It's Friday, so I picked something lighthearted and fun for the daily Kotaku science post. Did you know male wasp spiders snap their genitalia off inside the female during sex? Don't worry, they have two sets.

The animal kingdom is a funny place, filled with odd little discrepancies that keep people like University of Hamburg professor of behavioral ecology Jutta Schneider on their toes. Jutta is the co-author of a study that determined that male spiders are far more interested in a female's virginity than her size.

First off, why even perform such a study? Who wants to watch two spiders having sex? It's all about the battle of the sexes, and perhaps a little bit about bringing males down a peg.

"Usually the general wisdom is that the male sex has a large number of sperm cells, so the male is rather unlimited [in fertilizing] as many females as he can find," said Jutta Schneider . . . co-author of the study published in the October issue of Animal Behaviour. "But it's very different in these spiders."

Theory would suggest that the larger the female spider, the more attractive she be to the opposite sex. This is because larger female spiders tend to be more fertile, and fertility helps keep the species going.

And hell, male spiders just like big butts. They can't lie. They can't even talk.

But there's something they like better than big butts: Firsties.

For male wasp spiders it's not so much about propagating the species as it is propagating their particular lineage. That's why they try to break off their genitalia inside the female during sex - to make sure no one else can mate with her later.

It's not as painful as it sounds. See, spiders have testes, but they don't have penises. Instead, they spin their ejaculate into a small web and store it on one of two special forelegs called pendipalps.

The male spider enters the female's web. The vibration brings her out, where she assumes the pose: Face down, ass up. the male spider approaches, and shoves one of these forelegs into one of her two genital ducts. Yes, spiders go two-for-two in the genitalia department.

Then things get weird.

"At the second of genital contact - it's very easy to observe - the female suddenly bends, and it looks like he stabs her," Schneider said. "Then he has only seconds to complete his mission before she starts to take silk out of her spinnerets" in order to ensnare him.

If the male spider is ensnared, the female will eat him. If he's quick enough he'll escape to have sex again, at least one more time before he runs out of dick legs.

In the actual study, 21 pairs of female spiders were tested, each consisting of one virgin and one non-virgin. Twelve males spiders mated with the virgins, while only one opted for the more experienced female. And while each female has two genital ducts, there is a pheromone secreted until one of them is plugged, so while a girl spider might be only half deflowered, to a make spider she's used goods.

So why do male spiders prefer virgins? Aside from the better chance of the coupling being successful, I'd say there's less of a chance the female would let the male escape the second time around.

So there you have it: Plenty of fun spider facts to make your Friday special.

I'll leave you with one more. Male spiders can tell if their mate is a sibling. Researchers can tell, because male spiders spend less time on sex with their siblings than they do strangers.